Sextant



June 15, 1948. P. FERLEN Y 2,443,332

. :SEXTANT 7 Filed July 20, 1944 2 Sheets-Sheet 1- 'NYEZNTOR .RUSSELLRFKRLEN -ATT0RNE:Y.

June 15, 1948. R; P. FE'RLEN ,3

- SEXTANT Filed July 20, 1944 2 Sheets-Sheet 2 /0 INVENTOR G RussELLPFERLEN Patented June 15, 1948 .U l T ED 2,443,382 2 SEXTANT' Russell Barry'Fe'rl'en, Minneapolis, Minn. Application July 20, 1944', Serial No. 545,859

4 Claims.

This invention relates to a sextant or instru ment for determining the elevation of certain bodie such as celestial bodies. Such textants are now commonly used on airplanes as well ason ships and other places. In making an observation of an object such as the sun or of a star the image of'said object is located in a certain manner with respect to a mirror in said sextant commonly in connection with a bubble of a bubble mechanism and when properly located a record is made onsaid sextant and the operator notes the time of observation. Heretofore the operator has used a time piece separate from the sextant for noting the time and he must take his eye from the sight opening of the sextant and look at the watch or other time piece in order to note the time.

It is an object of this invention to provide a sextant having a time piece carried therein and so disposed in relation toa mirror in which the image of the said bubble is observed so that when the operator has the image properly 10-- catedhe can at the same time, view the time piece and note the time without taking his eye from' the sight opening of thesextant.

It is a further object of the invention to provide a sextant comprising a casing in which a bubble mechanism is disposed, said casing having a sight opening, a mirror located so as to be viewed from said sight opening and in which the bubble of said bubble mechanism is reflected together with a time piece disposed beyond said for illuminating the dial of said time piece.

Theseand other objects and advantages of the invention will be fully set forth in the following description made in connection with the accompanyi-ng drawings in which like reference characters refer to similar parts throughout the several views and in which:

Fig. 1 is a view partly in side elevation and partly in vertical section of a sextant embodying the present invention, certain parts-being b ok aw Fig. 2' is a perspective view of a portion of the side of said sextant" opposite the side shown in Fig. .1;

Fig. 3' is a partial viewshowing the relation of certain parts of the device;

Fig. 4 is a partialviewsimilar to Fig; l showing shape in sideelevation shown in Fig. l and which is rather flat or narrow in transverse dimension as indicated in 2 The casing I 0" is" shownas having a projectingportionlfla' at one end in which are secured removable members 1 adapted to'hold' in place and'be removed for insert'ion of certain dry batteries. A sight operring is provided at one end of casing lfl'adj'ac'ent' which the operator can place his eye and'look' into the casing 10. An eyepiece 10-12 is provided at said sightopening. The line of vision of the operator having his eye adjacent-the eye piece or sight opening Hlbis indicated by the dot and dash line 12. Disposed in line with said sight opening is a glass or transparent plate I-3 shown extending in a slanting or diagonal direction across the line of vision [2. Plate I3 has a central portion thereof formed as a mirror on the side adiacent the sight opening and said mirrored portion F311 is preferably made circular in outline, Also disposed-in line wth the sight open ing and mirror is a collimating lens 18. A bubble mechanism is provided contained in a casing l4 anisrnis commonly used and is well known Iomp'rises-the-bubbl'e 15 which is movable quid disposed between transparent plates. It is thought further description of the same wilt be unnecessary. The bubble meehanismis' so 10- cated that the sum of the distances from the center of lens [8' to the center of mirror 13 and fromthe: center of mirror l3 to bubble 4 5 is equal to' the principal focus of lens 18. A la'mp' I6 is provided carried in a socket 1'! and said lamp is disposed so asto shine throughthe bubble rnechanis'm and so that the image of said bubble can beclearly seen on the surface of mirror lil'a which is'thus illuminated by lamp Hi; Lamp i6 will be supplied with current from a dry battery carried in casing 1 0. The portion of plate lfii'about the mirror 1 3d is'clear or transparent. The end Hlc of easing 1 0 is shown as cylindrical and a removable sleeve 10d is insertible therein having a knurled c'ap' portion l lle'. Portions 10d and We are readily removable and adapted use have a "dcomprising amovable bubble i 5. This bubble placed therein with one side against the end portion llle, a time piece I9 such as an ordinary watch or wrist watch. In the embodiment of the invention illustrated a wrist watch is shown having the usual wrist encircling strap portion |9a. The dial of watch I9 is substantially perpendicular to the line of sight or line I2 and is located at a distance from lens |8 substantially equal to the principal focus or principal focal distance of said lens. Carried on the rear of plate I3 is a mirror 20 having its mirrored surface directed toward the time piece I9 and disposed at an angle to the line l2. A lamp 2| is carried in a socket 22 and supplied with current from a suitable dry battery 23, which lamp 2| is disposed so that the light therefrom will be refiected from mirror 20 onto the dial of time piece H), which dial is at the inner side of time piece IS. The said dial |9b as shown in Fig. 3, is of larger diameter than the mirror |3a so that an outer annular portion of said dial and portions of the cooperating hands can be seen around mirror I311. At the other side of casng I is a cylindrical member or drum 25 which carries a tape 26 adapted to be marked by a small pencil 21 carried in a holder 28 which is moved across said tape by the operator pressing on a finger lever 29 disposed in convenient position for operation by the thumb of the left hand of the operator using the sextant. An index glass 3| is provided adjacent the sight opening at eye piece Illb in casing H] which may be moved to different positions about a shaft or sleeve 24. Shaft 24 has secured thereto an arm having a vernier scale adjacent its end which moves along another arcuate graduated scale (not shown) which is disposed at the side of easing |0 opposite that shown in Fig. 1. Drum 25 is geared to shaft 24 so that movement of said drum moves said arm and index glass 3|. The parts 25 to 3| are cmomon in sextants and form no part of the present invention and are merely mentioned to facilitate an understanding of the operation of the sextant.

In operation if an object such as a celestial body, as for instance the sun or a star 32, is to be observed the operator holds the sextant so that the top part of the casing lily is substantially horizontal. The operator will place his eye at the sight opening at the eye piece lb and will, with the thumb and fingers of the right hand, lightly grasp the drum 25. The drum is now rotated as necessary to bring the image of the celestial object such as the sun into the range of vision. Sight glass 3| is oscillated and the image of said object will be reflected from the surface of index glass 3| into the eye of the observer when index glass 3| comes into the correct position. Said arm secured to shaft 24 is simultaneously oscillated along said arcuate scale so that when the image is correctly positioned the elevation of the object will be indicated on said arcuate scale. The operator manipulates drum H] until the image of the object appears to be superimposed on the image of bubble H at the center of mirror l3a. With the image of the object and the image of the bubble l5 appearing as coinciding in the center of mirror |3a an ideal condition for a record is produced. When bubble i5 is in the center of mirror |3a the sextant is in proper or horizontal position with part lug horizontal. The operator now presses on finger piece 29 moving pencil 21 across the tape 26 to make a mark thereon. The rays from bubble l5 and Watch |9 after passing through lens |8 extend in lines parallel to line l2. In other words, the lens focuses the rays on bubble I5 and time piece |9 so that they can be clearly and sharply seen. When the operator manipulates the device to bring the image of the bubble l5 into the described position on mirror I30. in line with the image of the object, he can look past said mirror through the transparent portion of plate It and see the outer portion of dial |9b as illustrated in Fig. 3, and the numerals thereon. The outer portion of the hands of the watch or time piece Hi can also be seen and the operator can thus note the time simultaneously with the correct positioning of the bubble and image and with the operation of the finger piece 29. It is thus not necessary for the operator to take his eye from the eye piece and look away at a watch or other time piece. By simultaneously viewing the correctly positioned images and the time piece a much more accurate record can be obtained. As stated, the light is focused on dial Hi?) and bubble It") by lens I3. Several observations are usually taken. Afterwards the drum 25 can be turned to register each mark with pencil 2'! and the reading made on the scale. An average is then secured. The operation described where the operator looks through the eye piece Hlb is called an indirect operation since he does not look directly at the object 32. Such an operation is most commonly used when viewing. the sun since the sun is a little too bright to observe directly. The sides of casing ill at the portion 0h are spaced to form an opening and the operator can place his eye at said portion and directly view the star 32 which will be reflected from the surface of index glass 3| along the line l2. Otherwise the operation is the same as described. It will be understood that an opening is provided at portion lily of the casing for viewing the desired object.

In Fig. 4 a modification is shown in which a time piece such as a watch 35 is placed directly back of the mirror |3a so that the operator can view the outer portion of the dial when looking at mirror |3a. In such case the portion of the dial which is visible will be illuminated by lamp I6 which shines through the bubble mechanism M. In place of the mirror |3a shown in Figs. 1 and 3, a half-silvered glass plate 36 could be used having a light layer 36a of silver over its entire surface. (See Fig. 5.) Such a mirror refiects the image, yet it is possible to see through it and watch is could be seen through the mirror 36. Also the portion of plate l3 about mirror |3a could be omitted so watch 19 would be directly seen.

From the above description it will be seen that we have provided a novel structure of sextant and one which greatly facilitates noting the time of the reading. As above stated, the operator notes the time simultaneously with viewing the properly positioned images and making the record mark on the tape 26. The device is conveniently constructed so that if desired, the operator can place his own wrist watch in the portion |0d of the casing. The watch such as an ordinary wrist watch, can be easily and quickly inserted in the casing or removed therefrom. The device has been amply demonstrated in actual practice and found to be very successful and eflicient.

It will of course be understood that various changes may be made in the form, details, arrangement and proportions of the parts, without departing from the scope of applicants invention, which generally stated, consists in a device capable of carrying out the objects above set forth, in the parts and combinations of parts disclosed and defined in the appended claims.

What is claimed is:

1. A sextant structure comprising a casing having a sight opening through which a heavenly body may be observed, a bubble mechanism in said casing including a movable bubble, a mirror substantially circular in outline disposed to be seen through said sight opening in which said bubble is reflected, a transparent zone adjacent said mirror, movable means including a collimating lens for causing the image of said heavenly body to appear to coincide with the reflection of said bubble in said mirror, a time-piece disposed beyond said mirror having a dial disposed to be observed through said transparent portion by an observer having his eye at said sight opening and means for illuminating said time-piece whereby when said image and reflection are positioned as desired in said mirror said observer can simultaneously note the time without taking his eye from said sight opening.

2. A sextant structure having in combination, a casing, said casin having a sight opening adjacent one end thereof through which a heavenly body may be observed, a time-piece at the end of said casing opposite said sight opening and having a dial directed toward said sight opening, a removable portion at said last mentioned end of said casing for facilitating positioning of said time-piece, a bubble mechanism in said casing including a movable bubble, a mirror between said sight opening and time-piece disposed in the line of sight, said dial being of larger diameter than said mirror whereby an annular portion of said dial and the cooperating hands of said time-piece may be observed around said mirror and means including a collimating lens for causing the image of said heavenly body to appear to be in said mirror and adjacent the reflection of said bubble in said mirror whereby when said observer has said reflection of said bubble positioned as desired in said mirror and said image of said heavenly body appearing to be in the mirror as desired, he can simultaneously note the time without taking his eye from said eye-piece or otherwise moving said sextant.

3. A sextant structure comprising a casing having a sight opening through which a heavenly body may be observed, a collimating lens in said casing, a bubble mechanism in said casing including a movable bubble, a mirror positioned in the line of sight and viewed through said lens in which said bubble is reflected in the line of sight, a transparent zone about said mirror, means including a collimating lens for causing the image of said heavenly body to appear to be located in said mirror so that it can be brought into position substantially coincident with the reflection of said bubble in said mirror, a time-piece dial disposed beyond said mirror adapted to be observed through said transparent portion by an observer having his eye at said sight opening, said bubble and said dial being at the same distance from said mirror, said distance plus the distance from said mirror to said lens being substantially equal to the principal focal distance of said lens whereby when said image and reflection of said bubble are positioned as desired in said mirror, said observer can simultaneously note the time on the dial of said time-piece through said transparent zone without movement.

4. A sextant structure having in combination, a casing having a sight opening therein, an eyepiece at said opening through which a heavenly body may be observed, a movable sight glass for reflecting an image of said heavenly body so that it appears to be in the line of sight of said eyepiece, a bubble mechanism in said casing comprising a movable bubble, a mirror disposed in the line of sight and positioned so as to reflect an image of said bubble into the line of sight, a lens disposed in the line of sight between said mirror and eye-piece, a time-piece disposed beyond said mirror in the line of sight comprising a dial having numerals at its periphery and hands moving RUSSELL PARRY FERLEN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date Calhoun June 6, 1911 Bedell Nov. 5, 1912 Estoppey Mar. 11, 1919 Frederick et al Apr. 4, 1922 Schlaich Mar. 3, 1925 Boykow Feb. 26, 1929 Beij Feb. 26, 1929 Carbonara Oct. 29, 1930 Paulus et a1 July 1'7, 1934 Hagner Mar. 12, 1940 Crane et a1 Dec. 23, 1941 Link et a1 Oct.'3, 1944 FOREIGN PATENTS Country Date France Nov, 13, 1926 Number Number 

